The present invention relates to a blowing head specifically, designed for air impact sandbox moulding machines. In such machines, the box is first filled with sand and the same is then compacted in to consecutive operations, in one of which air is blown onto the sand mass, and in another of which a mechanical compacting takes place, the two operations being carried out successively and immediately, using the same head, which acts as a blowing means and as a mechanical compacting means.
The applicant himself is the holder of Spanish patent of invention 8703409, for a shooting mechanism for coreshooters, wherein the rammer, designed to be coupled to the sand cartridge, is hollow and houses therein a pop valve, that is triggered due to the pressure existing in a drum, which pressure arrives at the valve through the actual guide-columns for alternating displacement of the rammer in coupling and uncoupling to and from the sand cartridge, the pop valve being driven by the actual pressure in the drum, such that the pressure normally arrives at the packing piston through two chambers that are set against each other, a chamber through which blowing air passes on its way towards the cartridge and an auxiliary chamber established at the rear of the packing piston and through which the piston is held closed, while the pressure entering the auxiliary chamber from the drum is not discontinued, which comes about precisely when the shooting takes place.
Furthermore, and within the field of air impact sandbox moulding machines, subject hereof, the applicant himself is also the holder of Spanish patent of invention 8901201, regarding a number of improvements to this kind of machines, which improvements comprise placing a sandsupplying hopper at the mouth of the machine, under the hatch supplying batched sand, a mo&or, duly protected against sand discharges and making up the element driving a number of lower blades or vanes that spread out and level the sand within the compacting chamber, the assembly being enclosed by a release valve, that is disposed annularly outside the hopper and provided with an annular stopper, such that after the sand is batched, the motor causes the sand to be spread out and levelled within the box and its respective frame whereupon pneumatic compacting takes place by opening the annular stopper and suddenly releasing compressed air onto the compacting chamber, specifically onto the upper base of the mass of the sand-binder mixture.
However, in machines such as that disclosed in Spanish patent of invention 8901201 and in any other air impact sandbox moulding machines, the sand mass not only fills the sandbox, but a sizeable part of the upper frame, and given that the box must subsequently be levelled, all the sand housed in the frame will be wasted.
To overcome this problem, in some machines the box and the frame move to a station where additional mechanical compacting follows, either by means of manifold pneumatic or hydraulic rammers or by means of a single rammer, thereby to improve the compacting of the sand mould and at the same cut down on the waste.